When we see records being broken and unprecedented events such as this, the onus is on those who deny any connection to climate change to prove their case. Global warming has fundamentally altered the background conditions that give rise to all weather. In the strictest sense, all weather is now connected to climate change. Kevin Trenberth

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ILULISSAT, GREENLAND -- With his mountaineering gear, ropes, and a buddy system that keeps him anchored, Konrad Steffen rappels down cracks into the heart of Greenland's ice sheet.

One mistake and he's dead. The crevices he enters, called moulins, are like vertical caves, or deep wells. Or Arctic versions of black holes, some of them plunging to depths of 500 feet and consisting of ice more than 100,000 years old.

They are an unforgiving master of the laws of physics, ready to suck unprepared intruders down to wherever gravity will take them in one of the most slippery, remote, and harrowing places on Earth.

Mr. Steffen's motivation for entering moulins is to learn more about the physical properties of those ice shafts, especially how they drain melt water from the top of the Greenland ice sheet to its base and speed the calving of glaciers. The tools he uses include a rotating laser and sophisticated camera system provided by NASA's Jet Propulsion Laboratory.

A Swiss-born researcher, Mr. Steffen directs the University of Colorado's environmental science institute and is one of the world's top Greenland experts. He's been doing field work in the Arctic since 1975. He has camped on Greenland's ice sheet at least once every year since 1990, when he created a permanent outpost east of Ilulissat known as "Swiss Camp."

That camp became the base of an extensive climate-monitoring network that now consists of 22 stations spread across the ice sheet. Mr. Steffen maintains that network, transmitting hourly data via satellites so scientists can learn more about how the ice sheet is changing.

NASA, the World Meterological Organization, the National Academy of Sciences, and state departments in the United States and Greenland are among those funding that work.

He's proud of never having lost one of his crew members through the ice.

Mr. Steffen said he is well aware of the risks and is careful to take precautions, including his use of hand-held global-positioning system devices. "You have to do that. Otherwise, it's suicide," he said.

America is well-represented in Greenland and Antarctica by scientists working to unravel clues about our warming planet.

Jason Box of Ohio State University's Byrd Polar Research Center is a former student of Mr. Steffen's. In July, Mr. Box and a graduate student took a 21-hour boat ride down a rarely traveled fjord east of Uummannaq, a little heart-shaped fishing village in northwestern Greenland that's surrounded by water.

They spent three days hiking across some of Greenland's hilliest and roughest terrain -- all for better time-lapse photography of a remote glacier after installing or replacing a combination of cameras.

The painstaking efforts they took to get those images are to help Mr. Box and his colleague, Ian Howat, an OSU glaciologist, take a more holistic look at the factors influencing Greenland's historic ice melt.

NASA satellite images, lasers, infrared technology, saltwater gauges, climate monitors, radar, sediment cores, ice samples, and readings from the Arctic Ocean are just a few of their tools.

"The big picture is the glaciers are changing. Certainly, it's warming up there," said Mark Fahnestock, a University of New Hampshire researcher whose field work in Greenland this summer marked the latest of several expeditions for him.

"If you go back 15 years, there wasn't anybody talking about large-scale changes to the glaciers just around the corner," he said.

Modern research includes field work from Alaska to Antarctica, from the forests of eastern Europe to the tropics of South America and the mountains of Asia.

And locally, Ohio State University's Stone Laboratory on Gibraltar Island, near Put-in-Bay, has been studying the effects of climate change on Lake Erie, as have biologists at the Ohio Department of Natural Resources' Lake Erie fisheries unit in Sandusky.

The University of Michigan's biological research station just south of the Mackinac Bridge, on a 10,000-acre tract near Pellston, Mich., also is one of the nation's most renowned for climate research.

Much of the climate work done by government scientists and those in academic institutions relies on computer modeling.

New research that Oregon State University published this month in the journal Science appears to strengthen that methodology, establishing a stronger correlation between carbon dioxide levels and abrupt changes to the Earth's climate. That helps explain why Greenland is melting now, given the rise in carbon dioxide levels globally.

"In every historic sequence we observed, the abrupt warming of Greenland occurred about when carbon dioxide was at maximum levels," Ed Brook, an Oregon State University associate professor of geosciences, said.